U.S. patent application number 09/733145 was filed with the patent office on 2001-06-21 for finishing treatment of pigments in liquid or supercritical co2.
Invention is credited to Jung, Rudiger, Kund, Klaus, Nestler, Bernd, Schmidt, Martin U., Steiner, Rudolf, Unverdorben, Leonhard.
Application Number | 20010003959 09/733145 |
Document ID | / |
Family ID | 7932196 |
Filed Date | 2001-06-21 |
United States Patent
Application |
20010003959 |
Kind Code |
A1 |
Jung, Rudiger ; et
al. |
June 21, 2001 |
Finishing treatment of pigments in liquid or supercritical CO2
Abstract
The invention provides a process for aftertreating organic
pigments by causing the ground or unground crude organic pigment
and liquid or supercritical carbon dioxide to act on one
another.
Inventors: |
Jung, Rudiger; (Kelkheim,
DE) ; Kund, Klaus; (Langenscheid, DE) ;
Nestler, Bernd; (Frankfurt am Main, DE) ; Schmidt,
Martin U.; (Frankfurt am Main, DE) ; Unverdorben,
Leonhard; (Nidderau, DE) ; Steiner, Rudolf;
(Erlangen, DE) |
Correspondence
Address: |
CLARIANT CORPORATION
4331 CHESAPEAKE DR
ATTN: INDUSTRIAL PROPERTY DEPT
CHARLOTTE
NC
28216
US
|
Family ID: |
7932196 |
Appl. No.: |
09/733145 |
Filed: |
December 8, 2000 |
Current U.S.
Class: |
106/493 |
Current CPC
Class: |
C09B 67/0014 20130101;
C09B 67/0001 20130101; Y02P 20/54 20151101; C09B 67/0003
20130101 |
Class at
Publication: |
106/493 |
International
Class: |
C08K 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 10, 1999 |
DE |
19959661.1 |
Claims
1. A process for finishing organic pigments, which comprises
treating a ground or unground crude organic pigment with liquid or
supercritical carbon dioxide.
2. The process as claimed in claim 1, wherein the crude pigment is
used in the form of a dry powder, filter cake or presscake.
3. The process as claimed in claim 1, wherein the finishing is
conducted with supercritical CO.sub.2 at a temperature between
31.2.degree. C. and 250.degree. C. and a pressure between 73.8 bar
and 400 bar.
4. The process as claimed in claim 1, wherein the finishing is
conducted with supercritical CO.sub.2 at a temperature between 50
and 200.degree. C. and a pressure between 75 and 300 bar.
5. The process as claimed in claim 1, wherein the finishing is
conducted with liquid CO.sub.2 at a temperature between 10.degree.
C. and 31.2.degree. C.
6. The process as claimed in claim 1, wherein CO.sub.2 is employed
in a weight ratio CO.sub.2 to pigment of between 0.2:1 and
200:1.
7. The process as claimed in claim 1, wherein the finishing is
carried out from 10 minutes to 10 hours.
8. The process as claimed in claim 1, wherein the finishing is
conducted in the presence of water or organic solvent.
9. The process as claimed in claim 8, wherein the amount of water
or organic solvent added is at most the amount which dissolves in
the CO.sub.2 under the established pressure and temperature
conditions.
10. The process as claimed in claim 1, wherein the pigment is an
azo pigment or a polycyclic pigment.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention is in the field of organic color
pigments. It is known that organic pigments, especially azo
pigments, are precipitated from the synthesis solution as small
insoluble particles (primary crystallites) which require an
aftertreatment (finish). In the course of this treatment, it is
necessary to modify physical properties, such as crystal form,
crystal size and crystal quality, and also particle size
distribution, toward a desired optimum. If a crude pigment
presscake is in fact dried directly after synthesis and washing,
there is often considerable congregation of the primary particles
to form agglomerates and aggregates. This leads to pigments with
hard grains, weak in color and difficult to disperse, which are
often impossible to bring into a technically usable form, even by
milling. Polycyclic pigments are precipitated from the synthesis
solution usually as coarsely crystalline crude pigments, which need
to be subsequently finely divided by means of appropriate
techniques, such as milling, for example. In the majority of cases,
the prepigments thus obtained also require an aftertreatment in
order to obtain the desired physical properties.
[0002] The standard pigment finish is a thermal aftertreatment in
which improved crystal formation is achieved by heating the crude
pigment suspension or the pigment presscake, washed to remove
salts, isolated and pasted up again, in water and/or organic
solvents. In this process, the ultrafine fraction, which is
responsible in particular for the agglomeration tendency of the
pigments, is reduced and, consequently, a narrower particle size
distribution is obtained. In organic solvents, pigments of
particularly low solubility are aftertreated at temperatures of
from 80 to 150.degree. C. Solvents used for this purpose include,
for example, alcohols, glacial acetic acid, chlorobenzene,
o-dichlorobenzene, and dimethylformamide.
[0003] The finishing techniques which have been customary to date
are expensive in terms of apparatus and energy, since heating and
the distillative removal of the solvent are often conducted under
pressure. Since the majority of organic solvents are flammable,
appropriate measures must be taken for plant safety.
SUMMARY OF THE INVENTION
[0004] The object of the present invention was to provide an
appropriate finishing process for organic pigments which is
superior to the hitherto customary solvent finish in terms of
safety, environmental compatibility, and resource consumption.
[0005] It has been found that liquid or supercritical carbon
dioxide is, surprisingly, a suitable finishing medium for organic
pigments.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0006] The present invention accordingly provides a process for
aftertreating organic pigments, which comprises causing ground or
unground arrange crude organic pigment and liquid or supercritical
carbon dioxide to act on one another.
[0007] The procedure here is judiciously to filter the crude
pigment suspension which is present following pigment synthesis or
following a fine division, e.g., by grinding, to wash the solid
filter product, to dry the washed product to give the crude pigment
powder, and to add liquid or supercritical CO.sub.2.
[0008] Instead of the dried crude pigment powder it is also
possible to use a water-moist or solvent-moist crude pigment, e.g.,
a filter cake or presscake.
[0009] The aftertreatment of the invention is judiciously conducted
in a heatable autoclave with stirring apparatus. It is not
necessary to pump off the residual air still present in the
autoclave. Carbon dioxide may be added in the form of dry ice or by
pumping in gaseous or liquid CO.sub.2, the amount being calculated
such that the pressure which is established at the desired
temperature is a pressure at which CO.sub.2 is in the supercritical
or liquid state. The preferred temperature range is situated
between 31.2.degree. C. and 250.degree. C., with particular
preference between 50 and 200.degree. C., in particular between 80
and 180.degree. C., for supercritical CO.sub.2. The pressure which
is established is from 73.8 bar to preferably 400 bar, with
particular preference between 75 and 300 bar, in particular between
80 and 250 bar. For liquid CO.sub.2, the preferred temperature
range is from 10 to 31.2.degree. C., in particular from 20 to
31.degree. C. Relative to the weight of the crude pigment, the
CO.sub.2 is used judiciously in an amount (CO.sub.2: pigment) of
from (0.2:1) to (200:1), preferably from (0.5:1) to (10:1). The
duration of the aftertreatment may vary within wide limits, with
from 10 minutes to 10 hours being judicious and from 0.5 to 5 hours
being preferred. Subsequently, the autoclave is let down to
atmospheric pressure and emptied.
[0010] It may be advantageous to conduct the aftertreatment of the
invention in the presence of water or organic solvents, such as
hydrocarbons, alcohols, ethers, amines, carboxylic acids,
carboxylic esters or carboxamides, for example, such as
N-methylpyrrolidone, for example. In this case, the amount of water
or solvent added should preferably be at most that which is soluble
in carbon dioxide under the prevailing conditions. Thus, for
example, at 75.degree. C. and 200 bar, about 5 g of water are
soluble per kilogram of CO.sub.2.
[0011] The aftertreatment of the invention may be performed with
all organic color pigments, such as azo pigments and polycyclic
pigments. Azo pigments may be monoazo, disazo, disazocondensation,
naphthol, or metal complex pigments.
[0012] Particularly appropriate azo pigments are C.I. Pigment
Yellow 16, 32, 83, 97, 120, 151, 154, 155, 175, 180, 181, 191, 194,
213, Pigment Orange 34, 36, 38, 62, 72, 74, Pigment Red 53:2,
112,122, 137, 144, 170, 171, 175, 176, 185, 187, 188, 208, 214,
242, 247, 253; Pigment Violet 32; Pigment Brown 25.
[0013] Polycyclic pigments may be, for example, isoindolinone,
isoindoline, anthanthrone, thioindigo, quinophthalone,
anthraquinone, dioxazine, phthalocyanine, quinacridone, perylene,
perinone, diketopyrrolopyrrole, thiazoindigo and azomethine
pigments, especially Pigment Violet 19, 23, Pigment Blue 15,
Pigment Green 7, 36, 37, Pigment Red 122, Pigment Yellow 139.
[0014] It has been found that the aftertreatment of the invention
may replace the aqueous or solvent finish which has been customary
to date. Furthermore, with certain pigments, depending on
temperature, pressure, treatment period and addition of water,
there may surprisingly also be a change in other physical
properties, such as the crystal modification or the ratio of the
crystal modifications formed, for example.
[0015] For example, the aftertreatment of the invention starting
from crude a-phase P.R. 170 produces a finished P.R. 170 having a
.gamma.-phase fraction.
EXAMPLES
[0016] In the examples below, the coloristic properties of the
pigment samples obtained were determined by comparative
measurements in the alkyd-melamine baking varnish AM 5; the
untreated samples were used in each case as the reference. The
brightening was evaluated by colorimetry in the CIELAB system in
accordance with DIN 6174; measurement was carried out on a PCM
instrument from Gardner, with the mean being formed in each case
from three individual values. The masstone was evaluated visually
under an assessment lamp in accordance with ASTM D1729 using
daylight (CIE D65).
Example 1
[0017] (comparative example)
[0018] A suspension of 90 g of P.R. 170 (.alpha. phase) in 1.7 1 of
water was admixed with 480 ml of isobutanol and the mixture was
stirred in an autoclave at a temperature of 140.degree. C. for 1
hour. After the autoclave had been cooled and let down, its
contents were transferred to a distillation apparatus and the
solvent was separated off by steam distillation. The aqueous
pigment suspension obtained was filtered, the filter cake was
washed with 8 1 of water, and the washed product was dried in a
drying oven at 100.degree. C. for 15 hours. This gives P.R. 170 in
the .beta. phase.
Examples 2 to 7
[0019] CO.sub.2 finish
[0020] 100 g of crude Pigment Red 170 (powder, .alpha. phase) were
charged to a 1.7 l autoclave. After heating to 139.degree. C., a
pressure of 83 bar was established by pumping in carbon dioxide.
After the contents of the autoclave had heated up and the set
conditions were constant, the pigment was maintained under these
conditions for 1 hour, 4 hours or 5 hours. Following a 1 0-minute
cooling phase, the autoclave was let down and the pigment was
removed.
[0021] The finishing conditions were varied in accordance with the
table below:
1 Finishing conditions Ex. t T p Crystal phase Colorimetrics No.
[h] [.degree. C.] [bar] Main/secondary CS dH dC -- -- -- untreated
.alpha. Reference 2 1 139 83 .gamma. high proportion a) f) h)
.alpha. and .beta. 3 1 140 238 .gamma. high proportion b) f) i)
.alpha. and .beta. 4 4 138 80 .gamma. fairly large b) e) i)
fractions .alpha. and .beta. 5 4 139 238 .gamma. approx. 30%
.beta., b) f) i) distinct fractions .alpha. 6 5 150 240 1 h .gamma.
approx. 30% .beta., b) d) g) 139.degree. C., distinct fractions 4 h
.alpha. 150.degree. C. 7 4 173 240 .gamma. approx. 20% .beta. c) d)
j) 8 4 42 80 .alpha. a) d) h) 9 4 27 70 liquid CO.sub.2 .alpha. a)
d) g) a) noticeably stronger in color b) markedly stronger in color
c) significantly stronger in color d) somewhat yellower e)
noticeably bluer f) substantially bluer g) a trace cleaner h)
noticeably cleaner i) markedly cleaner j) significantly cleaner
Example 10
[0022] CO.sub.2 finish with addition of water
[0023] 100 g of crude P. Red 170 (powder, .alpha. phase) were
charged to an autoclave. Prior to the addition of carbon dioxide, 3
g of water in addition were introduced into the autoclave. The
system was heated to 139.degree. C., a pressure of 240 bar was
established by pumping in CO.sub.2, and the pigment was stirred
under these conditions for 4 hours. After cooling, the finished
pigment was removed: the ratio of the .gamma. phase to the .beta.
phase is about 7:3. The product is meaningfully stronger in color,
noticeably bluer and substantially cleaner than the reference.
[0024] The .alpha. phase of P.R. 170 is understood as that crystal
modification which is characterized by the following lines in the
X-ray powder diagram (Cu K.sub..alpha. radiation, 2.THETA. values
in degrees): 7.6 (strong), 25.7 (strong), 5.2, 8.2, 11.7, 13.5,
15.9, 18.9, 23.5 (all moderately strong).
[0025] The .beta. phase of P.R. 170 is understood as that crystal
modification which is characterized by the following lines in the
X-ray powder diagram: 25.5 (strong), 7.1, 8.2, 11.3, 12.8, 15.1,
17.9 (all weak).
[0026] The .gamma. phase is distinguished by the following lines:
25.7 (strong), 7.3, 11.3, 12.9, 15.4, 18.2 (all moderately
strong).
[0027] All line positions of all modifications of all pigments are
subject to an inaccuracy of .+-.0.2.degree..
Example 11
[0028] The procedure of example 10 is repeated but using P.R.53:2
(powder, .alpha. phase) instead of P.Red 170. A mixture of .alpha.-
and .gamma. phase is obtained in a ratio of approximately 1:1,
which is characterized by the following lines in the X-ray powder
diagram: 4.4, 5.0, 5.7 (all strong), 25.0, 25.8 (both moderately
strong), 6.6, 8.7, 9.7, 10.1, 13.8, 14.5, 15.3, 16.7, 17.7, 18.0,
18.5, 23.2, 26.5 (all weak).
[0029] The product formed is somewhat redder than the initial
pigment.
Examples 12 to 15
[0030] 100 g of powder of the following crude pigments were charged
to a 1.7 l autoclave. After heating to 140.degree. C., a pressure
of 240 bar was established by pumping in carbon dioxide and the
pigment was held under these conditions for 4 hours. Subsequently,
the autoclave was let down and the finished pigment removed:
[0031] 12) C.I. Pigment Yellow 151
[0032] 13) C.I. Pigment Yellow 180
[0033] 14) C.I. Pigment Yellow 83
[0034] 15) C.I. Pigment Orange 36
[0035] In all cases, a soft-grained pigment featuring good
performance properties was obtained.
Example 16
[0036] Polycyclic pigment
[0037] 100 g of powder of the C.I. Pigment Red 122 (crude pigment)
were charged to a 1.7 l autoclave. After heating to 140.degree. C.,
a pressure of 240 bar was established by pumping in carbon dioxide
and the pigment was held under these conditions for 4 hours.
Subsequently, the autoclave was let down and the finished pigment
removed. A soft-grained pigment featuring good performance
properties was obtained.
Example 17
[0038] Polycyclic pigment with water
[0039] 100 g of powder of the C.I. Pigment Violet 23 (crude
pigment) and 20 g of water were charged to a 1.7 l autoclave. After
heating to 125.degree. C., a pressure of 240 bar was established by
pumping in carbon dioxide and the pigment was held under these
conditions for 4 hours. Subsequently, the autoclave was let down
and the finished pigment removed. A soft-grained pigment featuring
good performance properties was obtained.
Example 18
[0040] Finish with addition of NMP (N-methylpyrrolidin-2-one)
[0041] 100 g of reddish brown crude pigment P.Y. 213 and 4.9 g of
NMP were charged to a 1.7 l autoclave. After heating to 160.degree.
C., a pressure of 243 bar was established by pumping in CO.sub.2
and the pigment was stirred under these conditions for 4 hours.
After letdown, the finished pigment was removed.
[0042] In comparison to the reddish brown colored initial pigment
which was difficult to disperse in the AM 5 varnish, the product
obtained is yellow, readily dispersible and suitable, for example,
for producing metallic paints.
* * * * *